Bsi bs en 61158 5 4 2014

BS EN 61158-5-4:2014

BSI Standards Publication

Industrial communication
networks — Fieldbus
specifications
Part 5-4: Application layer service
definition — Type 4 elements


BRITISH STANDARD

BS EN 61158-5-4:2014
National foreword

This British Standard is the UK implementation of EN 61158-5-4:2014. It
is identical to IEC 61158-5-4:2014. It supersedes BS EN 61158-5-4:2008
which is withdrawn.
The UK participation in its preparation was entrusted to Technical Committee AMT/7, Industrial communications: process measurement and
control, including fieldbus.
A list of organizations represented on this committee can be obtained on
request to its secretary.
This publication does not purport to include all the necessary provisions of
a contract. Users are responsible for its correct application.
© The British Standards Institution 2014.
Published by BSI Standards Limited 2014
ISBN 978 0 580 79454 4
ICS 25.040.40; 35.100.70; 35.110

Compliance with a British Standard cannot confer immunity from

legal obligations.

This British Standard was published under the authority of the
Standards Policy and Strategy Committee on 31 October 2014.

Amendments/corrigenda issued since publication
Date

Text affected


BS EN 61158-5-4:2014

EUROPEAN STANDARD

EN 61158-5-4

NORME EUROPÉENNE
EUROPÄISCHE NORM

October 2014

ICS 25.040.40; 35.100.70; 35.110

Supersedes EN 61158-5-4:2008

English Version

Industrial communication networks - Fieldbus specifications Part 5-4: Application layer service definition - Type 4 elements
(IEC 61158-5-4:2014)

Réseaux de communication industriels - Spécifications des
bus de terrain - Partie 5-4: Définition des services de la
couche application - Eléments de type 4
(CEI 61158-5-4:2014)

Industrielle Kommunikationsnetze - Feldbusse Teil 5-4: Dienstfestlegungen des Application Layer
(Anwendungsschicht) - Typ 4-Elemente
(IEC 61158-5-4:2014)

This European Standard was approved by CENELEC on 2014-09-22. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels

© 2014 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN 61158-5-4:2014 E

BS EN 61158-5-4:2014
EN 61158-5-4:2014

-2-

Foreword
The text of document 65C/763/FDIS, future edition 2 of IEC 61158-5-4, prepared by
SC 65C “Industrial networks” of IEC/TC 65 “Industrial-process measurement, control and automation"
was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as EN 61158-5-4:2014.
The following dates are fixed:
•

latest date by which the document has to be
implemented at national level by
publication of an identical national
standard or by endorsement

(dop)

2015-06-22

•

latest date by which the national
standards conflicting with the
document have to be withdrawn

(dow)

2017-09-22

This document supersedes EN 61158-5-4:2008.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such
patent rights.
This document has been prepared under a mandate given to CENELEC by the European Commission
and the European Free Trade Association.

Endorsement notice
The text of the International Standard IEC 61158-5-4:2014 was approved by CENELEC as a
European Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standards indicated:

1)

IEC 61158-1:2014

NOTE

Harmonized as EN 61158-1:2014 (not modified).

IEC 61784-1:2014

NOTE

Harmonized as EN 61784-1:2014 (not modified).

IEC 61784-2:2014

NOTE

Harmonized as EN 61784-2

To be published.

1)

(not modified).


BS EN 61158-5-4:2014
EN 61158-5-4:2014

-3-

Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
NOTE 1 When an International Publication has been modified by common modifications, indicated by (mod), the relevant
EN/HD applies.
NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available here:
www.cenelec.eu

Publication

Year

Title

IEC 61158-3-4

2014

Industrial communication networks EN 61158-3-4
Fieldbus specifications Part 3-4: Data-link layer service definition Type 4 elements

2)

-

IEC 61158-4-4

2014

Industrial communication networks Fieldbus specifications Part 4-4: Data-link layer protocol
specification - Type 4 elements

EN 61158-4-4

2)

-

IEC 61158-6-4

2014

Industrial communication networks Fieldbus specifications Part 6-4: Application layer protocol
specification - Type 4 elements

EN 61158-6-4

2)

-

IEC 61158-6

Series

Industrial communication networks Fieldbus specifications Part 6: Application layer protocol
specification

EN 61158-6

Series

ISO/IEC 7498-1

-

Information technology - Open Systems
Interconnection - Basic reference model:
The basic model

-

-

ISO/IEC 7498-3

-

Information technology - Open Systems
Interconnection - Basic reference model:
Naming and addressing

-

-

ISO/IEC 8822

-

Information technology - Open Systems
Interconnection - Presentation service
definition

-

-

ISO/IEC 8824-1

-

Information technology - Abstract Syntax
Notation One (ASN.1): Specification of
basic notation

-

-

ISO/IEC 9545

-

Information technology - Open Systems
Interconnection - Application layer
structure

-

-

2)

To be published.

EN/HD

Year

BS EN 61158-5-4:2014
EN 61158-5-4:2014

-4-

Publication

Year

Title

EN/HD

ISO/IEC 10731

-

Information technology - Open Systems
Interconnection - Basic Reference Model Conventions for the definition of OSI
services

-

ISO/IEC/IEEE
60559

-

Information technology - Microprocessor

Systems - Floating-Point arithmetic

-

-

Year


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BS EN 61158-5-4:2014
IEC 61158-5-4:2014 © IEC 2014

CONTENTS
INTRODUCTION ..................................................................................................................... 6
1

Scope ............................................................................................................................... 7

2

1.1 General ................................................................................................................... 7
1.2 Specifications .......................................................................................................... 8
1.3 Conformance ........................................................................................................... 8
Normative references ....................................................................................................... 8

3

Terms and definitions ....................................................................................................... 9

4

3.1 ISO/IEC 7498-1 terms ............................................................................................. 9
3.2 ISO/IEC 8822 terms ................................................................................................ 9
3.3 ISO/IEC 9545 terms ................................................................................................ 9
3.4 ISO/IEC 8824-1 terms ........................................................................................... 10
3.5 Fieldbus data-link layer terms ................................................................................ 10
3.6 Fieldbus application layer specific definitions ........................................................ 10
3.7 Abbreviations and symbols .................................................................................... 16
3.8 Conventions .......................................................................................................... 17
Concepts ........................................................................................................................ 20

5

4.1
4.2
4.3
4.4
4.5
4.6
4.7
4.8
4.9
Type

Overview ............................................................................................................... 20
Architectural relationships ..................................................................................... 21
Fieldbus Application Layer structure ...................................................................... 23
Fieldbus Application Layer naming and addressing ............................................... 35

Architecture summary ............................................................................................ 35
FAL service procedures ......................................................................................... 36
Common FAL attributes ......................................................................................... 37
Common FAL service parameters .......................................................................... 37
APDU size ............................................................................................................. 38
4 communication model specification ..................................................................... 38

5.1 Concepts ............................................................................................................... 38
5.2 Variable ASE ......................................................................................................... 45
5.3 Application relationship ASE ................................................................................. 64
Bibliography .......................................................................................................................... 71
Figure 1 – Relationship to the OSI basic reference model ..................................................... 21
Figure 2 – Architectural positioning of the fieldbus Application Layer .................................... 22
Figure 3 – Client/server interactions ..................................................................................... 24
Figure 4 – Pull model interactions ......................................................................................... 25
Figure 5 – Push model interactions ....................................................................................... 26
Figure 6 – APOs services conveyed by the FAL .................................................................... 27
Figure 7 – Application entity structure ................................................................................... 29
Figure 8 – Example FAL ASEs .............................................................................................. 30
Figure 9 – FAL management of objects ................................................................................. 31
Figure 10 – ASE service conveyance .................................................................................... 32
Figure 11 – Defined and established AREPs ......................................................................... 34
Figure 12 – FAL architectural components ............................................................................ 36


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Figure 13 – FAL AE .............................................................................................................. 39
Figure 14 – Summary of the FAL architecture ....................................................................... 42
Figure 15 – FAL service procedure overview......................................................................... 43
Figure 16 – Time sequence diagram for the confirmed services ............................................ 44
Figure 17 – Time sequence diagram for unconfirmed services .............................................. 45
Table 1 – REQUEST service parameters .............................................................................. 60
Table 2 – RESPONSE service parameters ............................................................................ 61
Table 3 – Error codes by source ........................................................................................... 62
Table 4 – Reserve REP service parameters .......................................................................... 62
Table 5 – Free AREP service parameters ............................................................................. 63
Table 6 – Get REP attribute service parameters ................................................................... 63
Table 7 – Set REP attribute service parameters .................................................................... 64
Table 8 – AR send service parameters ................................................................................. 68
Table 9 – AR acknowledge service parameters ..................................................................... 68
Table 10 – AR get attributes service parameters ................................................................... 69
Table 11 – AR set attributes service parameters ................................................................... 69


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BS EN 61158-5-4:2014
IEC 61158-5-4:2014 © IEC 2014

INTRODUCTION
This part of IEC 61158 is one of a series produced to facilitate the interconnection of
automation system components. It is related to other standards in the set as defined by the
“three-layer” fieldbus reference model described in IEC 61158-1.
The application service is provided by the application protocol making use of the services
available from the data-link or other immediately lower layer. This standard defines the
application service characteristics that fieldbus applications and/or system management may

exploit.
Throughout the set of fieldbus standards, the term “service” refers to the abstract capability
provided by one layer of the OSI Basic Reference Model to the layer immediately above.
Thus, the application layer service defined in this standard is a conceptual architectural
service, independent of administrative and implementation divisions.


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–7–

INDUSTRIAL COMMUNICATION NETWORKS –
FIELDBUS SPECIFICATIONS –
Part 5-4: Application layer service definition –
Type 4 elements

1
1.1

Scope
General

The fieldbus application layer (FAL) provides user programs with a means to access the
fieldbus communication environment. In this respect, the FAL can be viewed as a “window
between corresponding application programs.”
This standard provides common elements for basic time-critical and non-time-critical
messaging communications between application programs in an automation environment and
material specific to Type 4 fieldbus. The term “time-critical” is used to represent the presence
of a time-window, within which one or more specified actions are required to be completed

with some defined level of certainty. Failure to complete specified actions within the time
window risks failure of the applications requesting the actions, with attendant risk to
equipment, plant and possibly human life.
This standard defines in an abstract way the externally visible service provided by the Type 4
fieldbus application layer in terms of
a) an abstract model for defining application resources (objects) capable of being
manipulated by users via the use of the FAL service,
b) the primitive actions and events of the service;
c) the parameters associated with each primitive action and event, and the form which they
take; and
d) the interrelationship between these actions and events, and their valid sequences.
The purpose of this standard is to define the services provided to
1) the FAL user at the boundary between the user and the application layer of the fieldbus
reference model, and
2) Systems Management at the boundary between the application layer and Systems
Management of the fieldbus reference model.
This standard specifies the structure and services of the Type 4 fieldbus application layer, in
conformance with the OSI Basic Reference Model (ISO/IEC 7498-1) and the OSI application
layer structure (ISO/IEC 9545).
FAL services and protocols are provided by FAL application-entities (AE) contained within the
application processes. The FAL AE is composed of a set of object-oriented application service
elements (ASEs) and a layer management entity (LME) that manages the AE. The ASEs
provide communication services that operate on a set of related application process object
(APO) classes. One of the FAL ASEs is a management ASE that provides a common set of
services for the management of the instances of FAL classes.
Although these services specify, from the perspective of applications, how request and
responses are issued and delivered, they do not include a specification of what the requesting
and responding applications are to do with them. That is, the behavioral aspects of the
applications are not specified; only a definition of what requests and responses they can

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BS EN 61158-5-4:2014
IEC 61158-5-4:2014 © IEC 2014

send/receive is specified. This permits greater flexibility to the FAL users in standardizing
such object behavior. In addition to these services, some supporting services are also defined
in this standard to provide access to the FAL to control certain aspects of its operation.
1.2

Specifications

The principal objective of this standard is to specify the characteristics of conceptual
application layer services suitable for time-critical communications, and thus supplement the
OSI Basic Reference Model in guiding the development of application layer protocols for timecritical communications.
A secondary objective is to provide migration paths from previously-existing industrial
communications protocols. It is this latter objective which gives rise to the diversity of services
standardized as the various Types of IEC 61158, and the corresponding protocols
standardized in IEC 61158-6 series.
This specification may be used as the basis for formal application programming interfaces.
Nevertheless, it is not a formal programming interface, and any such interface will need to
address implementation issues not covered by this specification, including
a) the sizes and octet ordering of various multi-octet service parameters, and
b) the correlation of paired request and confirm, or indication and response, primitives.
1.3

Conformance

This standard does not specify individual implementations or products, nor does it constrain

the implementations of application layer entities within industrial automation systems.
There is no conformance of equipment to this application layer service definition standard.
Instead, conformance is achieved through implementation of conforming application layer
protocols that fulfill the Type 2 application layer services as defined in this standard.

2

Normative references

The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
NOTE All parts of the IEC 61158 series, as well as IEC 61784-1 and IEC 61784-2 are maintained simultaneously.
Cross-references to these documents within the text therefore refer to the editions as dated in this list of normative
references.

IEC 61158-3-4:2014, Industrial communication networks – Fieldbus specifications – Part 3-4:
Data-link layer service definition – Type 4 elements
IEC 61158-4-4:2014, Industrial communication networks – Fieldbus specifications – Part 4-4:
Data-link layer protocol specification – Type 4 elements
IEC 61158-6-4:2014, Industrial communication networks – Fieldbus specifications – Part 6-4:
Application layer protocol specification – Type 4 elements
IEC 61158-6 (all subparts), Industrial communication networks – Fieldbus specifications –
Part 6: Application layer protocol specification
ISO/IEC 7498-1, Information technology – Open Systems Interconnection – Basic Reference
Model – Part 1: The Basic Model


BS EN 61158-5-4:2014

IEC 61158-5-4:2014 © IEC 2014

–9–

ISO/IEC 7498-3, Information technology – Open Systems Interconnection – Basic Reference
Model – Part 3: Naming and addressing
ISO/IEC 8822, Information technology – Open Systems Interconnection – Presentation
service definition
ISO/IEC 8824-1, Information
Specification of basic notation

technology

–

Abstract

Syntax

Notation

One

(ASN.1):

ISO/IEC 9545, Information technology – Open Systems Interconnection – Application Layer
structure
ISO/IEC 10731, Information technology – Open Systems Interconnection – Basic Reference
Model – Conventions for the definition of OSI services
ISO/CEI/IEEE 60559, Information technology – Microprocessor Systems – Floating-Point

arithmetic

3

Terms and definitions

For the purposes of this document, the following terms as defined in these publications apply:
3.1

ISO/IEC 7498-1 terms

a) application entity
b) application process
c) application protocol data unit
d) application service element
e) application entity invocation
f)

application process invocation

g) application transaction
h) real open system
i)
3.2

transfer syntax
ISO/IEC 8822 terms

For the purposes of this document, the following terms as defined in ISO/IEC 8822 apply:
a) abstract syntax

b) presentation context
3.3

ISO/IEC 9545 terms

For the purposes of this document, the following terms as defined in ISO/IEC 9545 apply:
a) application-association
b) application-context
c) application context name
d) application-entity-invocation
e) application-entity-type
f)

application-process-invocation


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IEC 61158-5-4:2014 © IEC 2014

g) application-process-type
h) application-service-element
i)
3.4

application control service element
ISO/IEC 8824-1 terms

For the purposes of this document, the following terms as defined in ISO/IEC 8824-1 apply:

a) object identifier
b) type
3.5

Fieldbus data-link layer terms

For the purposes of this document, the following terms apply.
a) DL-Time
b) DL-Scheduling-policy
c) DLCEP
d) DLC
e) DLPDU
f)

DLSDU

g) DLSAP
h) fixed tag
i)

generic tag

j)

link

k) network address
l)

node address

m) node
n) tag
o) scheduled
p) unscheduled
3.6

Fieldbus application layer specific definitions

For the purposes of this standard, the following terms and definitions apply.
3.6.1
application
function or data structure for which data is consumed or produced
3.6.2
application objects
multiple object classes that manage and provide a run time exchange of messages across the
network and within the network device
3.6.3
application process
part of a distributed application on a network, which is located on one device and
unambiguously addressed
3.6.4
application process identifier
distinguishes multiple application processes used in a device


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3.6.5
application process object
component of an application process that is identifiable and accessible through an FAL
application relationship
Note 1 to entry: Application process object definitions are composed of a set of values for the attributes of their
class (see the definition for Application Process Object Class Definition). Application process object definitions
may be accessed remotely using the services of the FAL Object Management ASE. FAL Object Management
services can be used to load or update object definitions, to read object definitions, and to dynamically create and
delete application objects and their corresponding definitions.

3.6.6
application process object class
class of application process objects defined in terms of the set of their network-accessible
attributes and services
3.6.7
application relationship
cooperative association between two or more application-entity-invocations for the purpose of
exchange of information and coordination of their joint operation
Note 1 to entry: This relationship is activated either by the exchange of application-protocol-data-units or as a
result of preconfiguration activities.

3.6.8
application relationship application service element
application-service-element that provides the exclusive
terminating all application relationships

means

for

establishing

and

3.6.9
application relationship endpoint
context and behavior of an application relationship as seen and maintained by one of the
application processes involved in the application relationship
Note 1 to entry: Each application process involved in the application relationship maintains its own application
relationship endpoint.

3.6.10
attribute
description of an externally visible characteristic or feature of an object
Note 1 to entry: The attributes of an object contain information about variable portions of an object. Typically, they
provide status information or govern the operation of an object. Attributes may also affect the behaviour of an
object. Attributes are divided into class attributes and instance attributes.

3.6.11
behaviour
indication of how an object responds to particular events
3.6.12
bit-no
designates the number of a bit in a bitstring or an octet
3.6.13
channel
single physical or logical link of an input or output application object of a server to the process

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IEC 61158-5-4:2014 © IEC 2014

3.6.14
class
set of objects, all of which represent the same kind of system component
Note 1 to entry: A class is a generalisation of an object; a template for defining variables and methods. All objects
in a class are identical in form and behaviour, but usually contain different data in their attributes.

3.6.15
class attributes
attribute that is shared by all objects within the same class
3.6.16
class code
unique identifier assigned to each object class
3.6.17
class specific service
service defined by a particular object class to perform a required function which is not
performed by a common service
Note 1 to entry:

A class specific object is unique to the object class which defines it.

3.6.18
client
a) object which uses the services of another (server) object to perform a task
b) initiator of a message to which a server reacts
3.6.19

communication objects
components that manage and provide a run time exchange of messages across the network
EXAMPLES: Connection Manager object, Unconnected Message Manager (UCMM) object, and Message Router
object.

3.6.20
connection
logical binding between application objects that may be within the same or different devices
Note 1 to entry: Connections may be either point-to-point or multipoint.

3.6.21
conveyance path
unidirectional flow of APDUs across an application relationship
3.6.22
dedicated AR
AR used directly by the FAL User
Note 1 to entry:

On Dedicated ARs, only the FAL Header and the user data are transferred.

3.6.23
default DL-address
value 126 as an initial value for DL-address, which has to be changed (e.g. by assignment of
a DL-address via the fieldbus) before operation with a DP-master (class 1)
3.6.24
device
physical hardware connected to the link
Note 1 to entry:

A device may contain more than one node.

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3.6.25
dynamic AR
AR that requires the use of the AR establishment procedures to place it into an established
state
3.6.26
endpoint
one of the communicating entities involved in a connection
3.6.27
error
discrepancy between a computed, observed or measured value or condition and the specified
or theoretically correct value or condition
3.6.28
error class
general grouping for related error definitions and corresponding error codes
3.6.29
error code
identification of a specific type of error within an error class
3.6.30
event
instance of a change of conditions
3.6.31
FAL subnet
subnetworks composed of one or more data link segments, identified by a subset of the

network address
Note 1 to entry:

FAL subnets are permitted to contain bridges but not routers.

3.6.32
FIFO variable
Variable Object class, composed of a set of homogeneously typed elements, where the first
written element is the first element that can be read
Note 1 to entry:
invocation.

On the fieldbus only one, complete element can be transferred as a result of one service

3.6.33
frame
denigrated synonym for DLPDU
3.6.34
interface
a) shared boundary between two functional units, defined by functional characteristics, signal
characteristics, or other characteristics as appropriate
b) collection of FAL class attributes and services that represents a specific view on the FAL
class


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3.6.35
invocation
act of using a service or other resource of an application process
Note 1 to entry: Each invocation represents a separate thread of control that may be described by its context.
Once the service completes, or use of the resource is released, the invocation ceases to exist. For service
invocations, a service that has been initiated but not yet completed is referred to as an outstanding service
invocation. Also for service invocations, an Invoke ID may be used to unambiguously identify the service invocation
and differentiate it from other outstanding service invocations.

3.6.36
index
address of an object within an application process
3.6.37
instance
actual physical occurrence of an object within a class that identifies one of many objects
within the same object class
EXAMPLE California is an instance of the object class state.
Note 1 to entry:

The terms object, instance, and object instance are used to refer to a specific instance.

3.6.38
instance attributes
attribute that is unique to an object instance and not shared by the object class
3.6.39
instantiated
object that has been created in a device
3.6.40
logical device
certain FAL class that abstracts a software component or a firmware component as an

autonomous self-contained facility of an automation device
3.6.41
manufacturer ID
identification of each product manufacturer by a unique number
3.6.42
management information
network-accessible information that supports managing the operation of the fieldbus system,
including the application layer
Note 1 to entry:

Managing includes functions such as controlling, monitoring, and diagnosing.

3.6.43
member
piece of an attribute that is structured as an element of an array
3.6.44
method
<object> a synonym for an operational service which is provided by the server ASE and
invoked by a client
3.6.45
module
hardware or logical component of a physical device


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3.6.46

network
set of nodes connected by some type of communication medium, including any intervening
repeaters, bridges, routers and lower-layer gateways
3.6.47
object
abstract representation of a particular component within a device, usually a collection of
related data (in the form of variables) and methods (procedures) for operating on that data
that have clearly defined interface and behaviour
3.6.48
object specific service
service unique to the object class which defines it
3.6.49
peer
role of an AR endpoint in which it is capable of acting as both client and server
3.6.50
physical device
automation or other network device
3.6.51
property
general term for descriptive information about an object
3.6.52
provider
source of a data connection
3.6.53
publisher
role of an AR endpoint that transmits APDUs onto the fieldbus for consumption by one or
more subscribers
Note 1 to entry: A publisher may not be aware of the identity or the number of subscribers and it may publish its
APDUs using a dedicated AR.

3.6.54
publishing manager
role of an AR endpoint in which it issues one or more confirmed service request APDUs to a
publisher to request the publisher to publish a specified object
Note 1 to entry: Two types of publishing managers are defined by this standard, pull publishing managers and
push publishing managers, each of which is defined separately

3.6.55
pull subscriber
type of subscriber that recognizes received confirmed service response APDUs as published
object data
3.6.56
resource
processing or information capability of a subsystem
3.6.57
route endpoint
object container containing Variable Objects of a variable class


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3.6.58
server
a) role of an AREP in which it returns a confirmed service response APDU to the client that
initiated the request
b) object which provides services to another (client) object
3.6.59

service
operation or function than an object and/or object class performs upon request from another
object and/or object class
3.6.60
subscriber
role of an AREP in which it receives APDUs produced by a publisher
3.7

Abbreviations and symbols
AE

Application Entity

AL

Application Layer

ALME

Application Layer Management Entity

ALP

Application Layer Protocol

APO

Application Object

AP

Application Process

APDU

Application Protocol Data Unit

API

Application Process Identifier

AR

Application Relationship

AREP

Application Relationship End Point

ASCII

American Standard Code for Information Interchange

ASE

Application Service Element

Cnf

Confirmation

CR

Communication Relationship

CREP

Communication Relationship End Point

DL-

(as a prefix) Data Link-

DLC

Data Link Connection

DLCEP

Data Link Connection End Point

DLL

Data Link Layer

DLM

Data Link-management

DLSAP

Data Link Service Access Point

DLSDU

DL-service-data-unit

DNS

Domain Name Service

DP

Decentralised Peripherals

FAL

Fieldbus Application Layer


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– 17 –

FIFO

First In First Out

HMI

Human-Machine Interface

ID

Identifier

IDL

Interface Definition Language

IEC

International Electrotechnical Commission

Ind

Indication

IP

Internet Protocol

ISO

International Organization for Standardization

LDev

Logical Device

LME

Layer Management Entity

OSI

Open Systems Interconnect

PDev

Physical Device

PDU

Protocol Data Unit

PL

Physical Layer

QoS

Quality of Service

REP

Route Endpoint

Req

Request

Rsp

Response

RT

Runtime

SAP

Service Access Point

SCL

Security Level

SDU

Service Data Unit

SEM

State event matrix

SMIB

System Management Information Base

SMK

System Management Kernel

STD

State transition diagram, used to describe object behaviour

VAO

Variable Object

3.8
3.8.1

Conventions
Overview

The FAL is defined as a set of object-oriented ASEs. Each ASE is specified in a separate
subclause. Each ASE specification is composed of two parts, its class specification, and its
service specification.
The class specification defines the attributes of the class. The attributes are accessible from
instances of the class using the Object Management ASE services specified in Clause 5 of
this standard. The service specification defines the services that are provided by the ASE.
3.8.2

General conventions

This standard uses the descriptive conventions given in ISO/IEC 10731.

3.8.3

Conventions for class definitions

Class definitions are described using templates. Each template consists of a list of attributes
for the class. The general form of the template is shown below:


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FAL ASE:
CLASS:
Class Name
CLASS ID:
PARENT CLASS:
ATTRIBUTES:

ASE Name

1
(o)
2
(o)
3
(m)
4
(m)
4.1
(s)
4.2
(s)

4.3
(s)
5.
(c)
5.1
(m)
5.2
(o)
6
(m)
6.1
(s)
6.2
(s)
SERVICES:

Key Attribute:
Key Attribute:
Attribute:
Attribute:
Attribute:
Attribute:
Attribute:
Constraint:
Attribute:
Attribute:
Attribute:
Attribute:
Attribute:

numeric identifier
name
attribute name(values)
attribute name(values)
attribute name(values)
attribute name(values)
attribute name(values)
constraint expression
attribute name(values)
attribute name(values)
attribute name(values)
attribute name(values)
attribute name(values)

1
2.
2.1
3

OpsService:
Constraint:
OpsService:
MgtService:

service name
constraint expression
service name
service name

(o)

(c)
(o)
(m)

BS EN 61158-5-4:2014
IEC 61158-5-4:2014 © IEC 2014

#
Parent Class Name

(1) The "FAL ASE:" entry is the name of the FAL ASE that provides the services for the class
being specified.
(2) The "CLASS:" entry is the name of the class being specified. All objects defined using
this template will be an instance of this class. The class may be specified by this
standard, or by a user of this standard.
(3) The "CLASS ID:" entry is a number that identifies the class being specified. This number
is unique within the FAL ASE that will provide the services for this class. When qualified
by the identity of its FAL ASE, it unambiguously identifies the class within the scope of
the FAL. The value "NULL" indicates that the class cannot be instantiated. Class IDs
between 1 and 255 are reserved by this standard to identify standardized classes. They
have been assigned to maintain compatibility with existing national standards. CLASS
IDs between 256 and 2048 are allocated for identifying user defined classes.
(4) The "PARENT CLASS:" entry is the name of the parent class for the class being
specified. All attributes defined for the parent class and inherited by it are inherited for
the class being defined, and therefore do not have to be redefined in the template for this
class.
NOTE The parent-class "TOP" indicates that the class being defined is an initial class definition. The parent class
TOP is used as a starting point from which all other classes are defined. The use of TOP is reserved for classes
defined by this standard.

(5) The "ATTRIBUTES" label indicate that the following entries are attributes defined for the
class.
a) Each of the attribute entries contains a line number in column 1, a mandatory (m) /
optional (o) / conditional (c) / selector (s) indicator in column 2, an attribute type label
in column 3, a name or a conditional expression in column 4, and optionally a list of
enumerated values in column 5. In the column following the list of values, the default
value for the attribute may be specified.


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– 19 –

b) Objects are normally identified by a numeric identifier or by an object name, or by
both. In the class templates, these key attributes are defined under the key attribute.
c) The line number defines the sequence and the level of nesting of the line. Each
nesting level is identified by period. Nesting is used to specify
i)

fields of a structured attribute (4.1, 4.2, 4.3),

ii)

attributes conditional on a constraint statement (5). Attributes may be mandatory
(5.1) or optional (5.2) if the constraint is true. Not all optional attributes require
constraint statements as does the attribute defined in (5.2).

iii)

the selection fields of a choice type attribute (6.1 and 6.2).

(6) The "SERVICES" label indicates that the following entries are services defined for the
class.
a) An (m) in column 2 indicates that the service is mandatory for the class, while an (o)
indicates that it is optional. A (c) in this column indicates that the service is
conditional. When all services defined for a class are defined as optional, at least one
has to be selected when an instance of the class is defined.
b) The label "OpsService" designates an operational service (1).
c) The label "MgtService" designates an management service (2).
d) The line number defines the sequence and the level of nesting of the line. Each
nesting level is identified by period. Nesting within the list of services is used to
specify services conditional on a constraint statement.
3.8.4
3.8.4.1

Conventions for service definitions
General

The service model, service primitives, and time-sequence diagrams used are entirely abstract
descriptions; they do not represent a specification for implementation.
3.8.4.2

Service parameters

Service primitives are used to represent service user/service provider interactions
(ISO/IEC 10731). They convey parameters which indicate information available in the
user/provider interaction. In any particular interface, not all parameters need be explicitly
stated.
The service specifications of this standard uses a tabular format to describe the component

parameters of the ASE service primitives. The parameters which apply to each group of
service primitives are set out in tables. Each table consists of up to five columns for the
1) Parameter name,
2) request primitive,
3) indication primitive,
4) response primitive, and
5) confirm primitive.


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BS EN 61158-5-4:2014
IEC 61158-5-4:2014 © IEC 2014

One parameter (or component of it) is listed in each row of each table. Under the appropriate
service primitive columns, a code is used to specify the type of usage of the parameter on the
primitive specified in the column:
M

parameter is mandatory for the primitive

U

parameter is a User option, and may or may not be provided depending on dynamic
usage of the service user. When not provided, a default value for the parameter is
assumed.

C

parameter is conditional upon other parameters or upon the environment of the

service user.

—

(blank) parameter is never present.

S

parameter is a selected item.

Some entries are further qualified by items in brackets. These may be
a)

a parameter-specific constraint:
“(=)” indicates that the parameter is semantically equivalent to the parameter in the
service primitive to its immediate left in the table.

b)

an indication that some note applies to the entry:
“(n)” indicates that the following note "n" contains additional information pertaining to
the parameter and its use.

3.8.4.3

Service procedures

The procedures are defined in terms of
•

the interactions between application entities through the exchange of fieldbus Application
Protocol Data Units, and

•

the interactions between an application layer service provider and an application layer
service user in the same system through the invocation of application layer service
primitives.

These procedures are applicable to instances of communication between systems which
support time-constrained communications services within the fieldbus Application Layer.

4
4.1

Concepts
Overview

The fieldbus is intended to be used in factories and process plants to interconnect primary
automation devices (e.g. sensors, actuators, local display devices, annunciators,
programmable logic controllers, small single loop controllers, and stand-alone field controls)
with control and monitoring equipment located in control rooms.
Primary automation devices are associated with the lowest levels of the industrial automation
hierarchy and perform a limited set of functions within a definite time window. Some of these
functions include diagnostics, data validation, and handling of multiple inputs and outputs.
These primary automation devices, also termed field devices, are located close to the process
fluids, the fabricated part, the machine, the operator and the environment. This use positions
the fieldbus at the lowest levels of the Computer Integrated Manufacturing (CIM) architecture.
Some of the expected benefits in using fieldbus are reduction in wiring, increase in amount of
data exchanged, wider distribution of control between the primary automation devices and the

control room equipment, and the satisfaction of time critical constraints.


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Clause 4 describes fundamentals of the FAL. Detailed descriptive information about each of
the FAL ASEs can be found in the “Overview” subclause of each of the Communication Model
specifications.
4.2

Architectural relationships

4.2.1

Relationship to the Application Layer of the OSI basic reference model

The functions of the FAL have been described according to OSI layering principles. However,
its architectural relationship to the lower layers is different, as shown in Figure 1.
–

The FAL includes OSI functions together with extensions to cover time-critical
requirements. The OSI Application Layer Structure standard (ISO/IEC 9545) was used as
a basis for specifying the FAL.

–

The FAL directly uses the services of the underlying layer. The underlying layer may be

the data link layer or any layer in between. When using the underlying layer, the FAL may
provide functions normally associated with the OSI Middle Layers for proper mapping onto
the underlying layer.

OSI AP

Fieldbus User Layer

OSI Application Layer

Fieldbus Application Layer

OSI Middle
Layers

(possibly non-existent)

OSI Data Link Layer

Data Link Layer

OSI Physical Layer

Physical Layer

Physical Medium

Physical Medium

Figure 1 – Relationship to the OSI basic reference model

4.2.2
4.2.2.1

Relationships to other fieldbus entities
General

The fieldbus Application Layer (FAL) architectural relationships, as illustrated in Figure 2,
have been designed to support the interoperability needs of time-critical systems distributed
within the fieldbus environment.
Within this environment, the FAL provides communications services to time-critical and nontime-critical applications located in fieldbus devices.
In addition, the FAL directly uses the Data Link Layer to transfer its application layer protocol
data units. It does this using a set of data transfer services and a set of supporting services
used to control the operational aspects of the Data Link Layer.


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BS EN 61158-5-4:2014
IEC 61158-5-4:2014 © IEC 2014

Fieldbus User

System Mgt

Fieldbus
Application Layer

ALME

Fieldbus

Data Link Layer

Figure 2 – Architectural positioning of the fieldbus Application Layer
4.2.2.2

Use of the fieldbus Data Link Layer

The fieldbus Application Layer (FAL) provides network access to fieldbus APs. It interfaces
directly to the fieldbus Data Link Layer for transfer of its APDUs.
The Data Link Layer provides various types of services to the FAL for the transfer of data
between Data Link endpoints (e.g. DLSAPs, DLCEPs).
4.2.2.3

Support for fieldbus applications

Fieldbus applications are represented to the network as application processes (APs). APs are
the components of a distributed system that may be individually identified and addressed.
Each AP contains an FAL application entity (AE) that provides network access for the AP.
That is, each AP communicates with other APs through its AE. In this sense, the AE provides
a window of visibility into the AP.
APs contain identifiable components that are also visible across the network. These
components are represented to the network as Application Process Objects (APO). They may
be identified by one or more key attributes. They are located at the address of the application
process that contains them.
The services used to access them are provided by APO-specific application service elements
(ASEs) contained within the FAL. These ASEs are designed to support user, function block,
and management applications.
4.2.2.4

Support for system management

The FAL services can be used to support various management operations, including
management of fieldbus systems, applications, and the fieldbus network.
4.2.2.5

Access to FAL layer management entities

One layer management entity (LME) may be present in each FAL entity on the network.
FALMEs provide access to the FAL for system management purposes.
The set of data accessible by the System Manager is referred to as the System Management
Information Base (SMIB). Each fieldbus Application Layer Management Entity (FALME)
provides the FAL portion of the SMIB. How the SMIB is implemented is beyond the scope of
this standard.